Lubricating composition



Patented Nov. 30, 1937 UNITED STATES PATENT oEEicE No Drawing. Application April 27, 1936, Serial No. 76,613

5 Claims.

This invention relates to improvements in lubricating oils and while the product contemplated thereby possesses properties which are desirable in an oil designed for use under any cir- 5 cumstances where the formation of sludge is a deleterious factor, my invention is particularly concerned with lubricating oils for internal combustion engines.

As is well known to those familiar with the 10 art, the operating conditions in the crank case of an internal combustion engine are conducive to the formation of heavy hydrocarbon bodies in the lubricating oil which precipitate as what is commonly known as sludge. This sludge, ac-

15 cumulates about the piston rings, locking them against their normabaction and as a consequence contributes to the pumping of oil. Sludge also tends to form about the valve stems, causing them to stick, and on the bearings, increasing their frictional resistance and counteracting the effect of the lubricant. Also the sludge accumulates in the oil lines, the screens and the In addition filters retarding its normal flow. such sludge is deposited or forms on the piston heads, ultimately breaking down into carbon, the sludge itself acting as a binder for the carbon and making its removal extremely difiicult.

It is a primary object of this invention to produce a lubricant consisting chiefly of a min 39 eral oil which contains an additional ingredient that will prevent the precipitation of sludge and thereby avoid the attending undesirable effects enumerated above. 7

It is 'a further object of this invention to 35 provide a lubricant of the class described which has a solvent action or an increased affinity for sludge which has already been formed in the crank case or on the engine parts, and is thereby effective to remove sludge deposits which have 40 previouslybeen formed.

With the foregoing object in mind, I have discovered that when diethylene oxide (sold commercially under the trade name ofDioxan) is added to an ordinary lubricating oil, that such 45 oil acquires the property of dissolving the sludge ordinarily attending its break down and willsatisfy the contemplated objectives pointed out above. Although the exact action which the diethylene oxide has upon the mineral oil is not 50 conclusively known, the effect obtained appears to be a change in the solvent action of the mineral oil itself rather than an independent action of the added ingredient. This presumption is based upon the observation that a very minute 55 amount, that is, as little as .05% of the diethylene oxide when added to an ordinary mineral lubricating oil, will render such oil capable of dissolving a mineral oil sludge and wfll in addition, presumably through this increased-solvent action, prevent precipitation of such sludge under the temperature and wearing conditions in which it is usually formed.

Although the minimum percentage of the diethylene oxide which experience indicates to be apparently preferable from a. practical stand- 10 point is, as pointed out above, in the neighborhood of .05%, it is possible that smaller amounts may be used with beneficial results depending upon how aggravated the conditions are under which the lubricant is used and also depending to a degree upon the physical characteristics of the mineral oil which forms the chief constituent of the particular lubricant in question.

The maximum amount of diethylene oxide which can satisfactorily be used to accomplish the desired results, must depend upon the specifications required in the finished product as well as the specifications or physical properties of the mineral oil to which the diethylene oxide is added. In this connection it should be pointed out that commercial diethylene oxide is a comparatively volatile compound having an initial boiling point in the neighborhood of 98 C. and a dry point of 108 C. (at 760 mm.) and so far as I have been able to determine, it possesses no lubricating value whatever. Diethylene oxide is soluble in mineral oils and as pointed out above apparently reacts with such oils in some manner so as to increase their sludge dissolving properties, If added in appreciable quantitiesto the mineral oil it tends to lower the flash and fire, points for such oils. The controlling property, therefore, of this ingredient is one of dilution and the limitation of the maximum amount of the materialto be used aside from the factor of cost is controlled by the permissible amount of dilution which can be carried by the particular mineral oil in question without having an injurious effect upon its lubricating properties.

The maximum amount of diethylene oxide which can be used therefore is to a large extent controlled by the properties of the original oil, the specifications required for the finished oil and the operating conditions under which the finished oil is to be used, such as the type of motor and the temperature at which the motor is operated. Probably a maximum figure for satisfactory all purpose operation inautomobile engines would be 10% of the diethylene oxide added to an ordinary mineral oil of automobile engine specifications. Since high temperature operating conditions may volatilize a certain amount of the diethylene oxide carrying its concentration down to a smaller percentage, I consider it preferable from the standpoint of economy in manufacture and also from the standpoint of high lubricating efliciency in the finished product, to employ a concentration of diethylene oxide in the mineral oil in the neighborhood of up to two per cent.

The preferred limits contemplated by this invention, therefore are from .05% to 2.0%, but as pointed out above, the amount of diethylene oxide added is controlled by several factors some of which may make it desirable to use a muchhigher percentage of this ingredient. For' example, instead of using an ordinary lubricating oil stock which will satisfy the standard specifications for this purpose as the basic stock, I may under some circumstances, find it desirable to use an original stock of much higher viscosity and flash and fire properties, diluting such stock with a much greater percentage of diethylene oxide to bring its specifications in to the predetermined range that will satisfy the requirements for automotive practice.

Broadly, therefore, the amount'of diethylene oxide used will be limited at its minimum value to an amount sufiicient to materially increase the sludge dissolving property of the mineral oil and the maximum amount used should be proportioned so as to form a product of predetermined lubricating oil specifications. Or, more specifically, the maximum amount of the diethylene oxide present should be within the permissible dilution range for the original mineral oil stock.

As has been indicated above,'the use of diethylene oxide in a mineral oil composition of the type described increases the sludge dissolving properties of the mineral oil so as to keep the sludge or sludge forming hydrocarbons in suspension and to bring any previously precipitated sludge into suspension or into solution. A

F lubricating composition of this character, therefore, will prevent the valves of an internal combustion engine from sticking, it will keep the rings free from sludge and carbon encrustations and in view of its sludge dissolving property I have discovered that it will dissolve the sludge formation from within the reservoirs, lines, screens and filters and from around the rings and the valve stems, permitting free flow of the oil and freeing the latter members from increased friction and sticking tendencies. Also it will dissolve the oxidized oil or sludge which acts as a binder for the carbon formed on the piston head and therefore facilitates the removal and prevents the accumulation of such carbon.

Although I have laid particular stress upon my invention as a lubricant composition formed at the point of manufacture, by adding diethylene oxide to a lubricant stock it will be seen that the results contemplated by this invention may be accomplished by adding diethylene oxide to an ordinary lubricating oil at the point of distribution or even by adding diethylene oxide to the lubricating oil in the crank case of an automobile engine or the like. My invention therefore in addition to the composition described above contemplates as a further feature, a method for increasing the sludge dissolving property of a mineral oil by adding diethylene oxide thereto.

It is to be understood that while I have herein described certain preferred ratios of the ingredients to the lubricating composition contemplated by this invention, that the invention is not limited to the specific proportions pointed out above, but includes within its scope such changes as may fairly come within the spirit of the appended claims.

I claim as my invention:

1. A lubricating'composition comprising mineral oil containing at least .05% diethylene oxide, the proportion of. diethylene oxide present being insufficient to materially alter the flash and fire and the viscosity characteristics of the min-- eral oil.

2. A lubricant composition comprising mineral oil containing diethylene oxide in an amount sufficient to materially increase the sludge dissolving property of the mineral oil, the amount of diethylene oxidepresent being insuflicient to materially change the flash and fire and viscosity characteristics of said mineral oil.

3. A lubricant composition comprising mineral oil containing diethylene oxide in amounts between substantially .05% and 2.0%.

4. A lubricant composition comprising mineral oil containingv diethylene oxide in amounts between substantially .05% and 10.0%.

5. A lubricant composition comprising mineral oil containing diethylene oxide in an amount sufi'icient to materially increase the sludge dis- 

